Authorities in Chile say all 12 people killed when a bus crashed into a mountain ravine Wednesday were Americans.

The accident occurred near the port city of Arica, about 2,000 kilometers north of the capital city of Santiago. The bus was carrying tourists from a cruise ship docked in Arica and operated by Celebrity Cruises.

The tourists were returning to the cruise ship after visiting a national park near the border with Bolivia.

At least two other passengers were injured. The cause of the crash is under investigation.

Officials with Celebrity Cruises say the victims had been on a private tour not affiliated with the cruise line at the time of the accident.